Clinical implications of subclinical hypothyroidism (SCH) are still matter of intense debate, resulting in the controversial discussion whether subclinical hypothyroidism should be treated. We performed a cohort study to evaluate the impact of subclinical hypothyroidism on vascular and overall mortality.

METHODS:

Between 02/1993 and 03/2004, a total of 103,135 persons attending the General Hospital Vienna with baseline serum thyrotropin (TSH, thyroid-stimulating hormone) and free thyroxin (fT4) measurements could be enrolled in a retrospective cohort study. Subclinical hypothyroidism was defined by elevated TSH ranging from 4.5 to 20.0 mIU/L and normal fT4 concentration (0.7-1.7 ng/dL). Overall and vascular mortality as primary endpoints were assessed via record linkage with the Austrian Death Registry.

RESULTS:

A total of 80,490 subjects fulfilled inclusion criteria of whom 3934 participants (3.7 %) were classified as SCH (868 males and 3066 females, median age 48 years). The mean follow-up among the 80,490 subjects was 4.1 years yielding an observation period of 373,301 person-years at risk. In a multivariate Cox regression model adjusted for age and gender TSH levels showed a dose-dependent association with all-cause mortality. The association between SCH and overall or vascular mortality was stronger in men below 60 years compared to older males or females.

CONCLUSION:

Our data support the hypothesis that SCH might represent an independent risk factor for overall and vascular mortality, especially in men below 60 years. Whether this group would benefit from replacement therapy should be evaluated in interventional studies.

9 Replies

I feel I "got away with it" and, although I had numerous symptoms, they were individually relatively mild. However, if I hadn't realised that thyroid was behind them, I could have gone through far, far more.

I keep wondering if the male:female ratio is changing - after all, it is widely accepted that thyroid disorder levels have been rising. There is no reason to assume that the geneder balance will remain as it has been historically.

Not noticed anything yet. I'm only on 50mcg, but won't push it as everytime I tried to self medicate with T4 containing meds, I had a bad reaction. It could well have been that I over did it (I do with everything). So far on the 50mcg, I've had no adverse reactions. I'll get blood tests next week.

I've been taking mine 1st thing. I take ZMA at night, which definitely helps sleep.

Good job I was 68 when diagnosed. Interesting about male/ female ratio. I was diagnosed with ankylosing spondylitis in my 20's and I seem to recall women were not thought to suffer from it then.We know different now. Part of the problem was difficulty to diagnose AS .